binman: Add an image header

It is useful to be able to quickly locate the FDT map in the image. An
easy way to do this is with a pointer at the start or end of the image.

Add an 'image header' entry, which places a magic number followed by a
pointer to the FDT map. This can be located at the start or end of the
image, or at a chosen location.

As part of this, update GetSiblingImagePos() to detect missing siblings.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/tools/binman/test/118_fdtmap_hdr_pos.dts b/tools/binman/test/118_fdtmap_hdr_pos.dts
new file mode 100644
index 0000000000..fd803f57fb
--- /dev/null
+++ b/tools/binman/test/118_fdtmap_hdr_pos.dts
@@ -0,0 +1,19 @@
+/dts-v1/;
+
+/ {
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	binman {
+		size = <0x400>;
+		sort-by-offset;
+		u-boot {
+			offset = <0x100>;
+		};
+		fdtmap {
+		};
+		image-header {
+			offset = <0x80>;
+		};
+	};
+};